It is known to manufacture plastic containers for use in the so-called hot fill process by injection molding preforms of plastic, such as PET, and blow-molding the preforms in a mold cavity. After molding, the resulting containers are discharged from the mold and packaged for shipment to another location for filling with a beverage, such as juice at an elevated temperature. After filling, the containers are capped and allowed to cool to ambient temperature for distribution to the ultimate consumer. This same basic process is used for filling with other liquids, edible and inedible, such as salad oil and shampoo. Some of these other liquids are filled at ambient temperature.
It is customary for the preforms to be injection molded at one location and transported to another location where they are blown into containers. At the blowing location, preforms are customarily fed in single file to a feeding mechanism which transfers the preforms to a conveyor which spaces them from one another and advances them in an open loop path through a pre-heat oven. In the pre-heat oven, the preforms are heated to a predetermined temperature by various means, such as radiant heaters. After the preforms are heated to the desired temperature, usually near the glass transition temperature (Tg) of the particular plastic from which the preform is molded, the preform is transferred into a blow-mold cavity. While in the blow-mold cavity, the preform is blown by means of compressed air into the shape of the mold cavity while preferably simultaneously being subjected to axial stretching to effect biaxial orientation of the container, all known in the art. After a brief residence period in the mold, the resulting blown container is discharged from the mold for packing and in the mold, the resulting blown container is discharged from the mold for packing and shipping to another location for filling.
The filling location can be at a completely separate plant location, or can be connected to the blow-molding equipment by means of a belt-type conveyor, such as where the blow-molding occurs at one plant location and filling at another location within the same plant.
It is customary to use belt-type conveyors to move containers from one location to another in a plant, particularly when non-carbonated liquids are involved. In carbonated filling systems, the containers are typically transported by the neck finish. It is also known to use chain-type conveyors in the pre-heat oven to engage the preforms at their neck finishes while they are being heated. Sidel of Le Havre France, manufactures a rotary preform transfer device which grips the preheated preforms about their necks and transfers them into the blow-mold. The device rotates much like a star-wheel, about a vertical axis, but has claw-like gripping elements which grip the preform about its neck finish and advance it in an arcuate path to a like gripper associated with the blow-mold. The gripper on the rotary transfer device is designed to release the preform only after the blow-mold gripper has actually gripped the preform. As a result, the preform is always under positive control as it transits through the pre-heat oven and the blow-mold apparatus. Such apparatus has been found particularly reliable in operation.
In an aseptic filling operation, after the container is blown from a preform, it is discharged from the blow-mold for sterilization, filling and capping. It is conventional practice to load the empty blown containers onto a conveyor belt which transports them to another plant location for sterilizing, filling and capping. At such location, the containers are initially spaced apart on the conveyor by various means, for example a screw-type conveyor for transfer between guide rails to a star-wheel which displaces the containers through various paths that pass through sterilization, filling and capping stations. This equipment is known in the art.
A significant problem with the above approach in the production of filled and capped blow-molded containers resides in the inefficiencies associated with the transfer of empty containers from one conveyor to another. During the transfer process, containers have a proclivity for jamming in the region of the screw conveyor transfer to a guide rail and star-wheel, particularly when empty containers are engaged by their bodies which deform-easily, thereby necessitating a shutdown of the entire line until the jam has been cleared. Considering the high production rates associated with modern container manufacturing and filling operations, shutdowns even as short as one half hour can be costly to the plant operator. Moreover, in an environment wherein containers are also sterilized prior to filling, additional inefficiencies occur because of the need to enter a sterile environment for unclogging a jam, and the time required for re-sterilization.
A common technique for high-speed filling of containers with liquids involves the use of a movable fill nozzle which penetrates the neck of a container and which retracts as filling progresses. With this technique, foaming is minimized, and this expedites accurate filling to a predetermined fill level. While this technique may be satisfactory in the hot-filling of containers, it is not desirable in aseptic filling where it is imperative that the fill nozzle not penetrate the container neck finish in order to maintain sterilization of the container and its contents and to avoid the potential for cross-contamination.
In capping filled containers, caps are normally fed down a chute and picked for application to containers as they move past a capping station. It is known that such equipment has a proclivity for jamming, which can necessitate a shutdown of the entire line to fix the course of the jam. Occasionally, a filled, but uncapped, container exits the capping machine and spills its contents. This necessitates clean up, not to mention loss of product. There have been some attempts to control the application of caps onto containers with some degree of precision in an effort to avoid this problem. However, the effectiveness of such equipment is not known.
In prior art practice, blow-molding systems operate at efficiencies above 95%, while filling/capping systems operate between 70-80%. Economical operation required decoupling these operations. A system is needed to increase the efficiency of filling/capping. This is particularly true with aseptic operations.
In addition to the reliability limitations associated with attempting to integrate disparate items of machinery, often produced by different companies, into an efficient operation, there is the problem of plant space limitations. Apparatus which can blow-mold and cap containers in a minimum of plant floor space is highly desirable both from an efficiency and a capital requirement standpoint.